Thetford iNDUS smart sanitisation

How to empty a motorhome toilet cassette like a pro (and stay off grid for a week)


“My motorhome toilet cassette prevents me from staying off grid for more than two to three days at a time.”

“I find it difficult to find a place to discharge my motorhome toilet cassette.”

“My biggest challenge when emptying my motorhome toilet cassette? Parking close enough to the discharge point.”

Emptying your motorhome toilet cassette, or your grey water tank is a job no owner we know likes. The act of emptying your toilet cassette and grey water tanks can be messy. The job can feel unhygienic at times. 

And, if you like being off grid, emptying your tanks is inconvenient. Your motorhome toilet cassette and grey water tanks tie you to campsites when you want to get off grid. Your motorhome is all about freedom. But, there’s an inconvenient fact that you need to empty your grey and black water tanks and fill up your fresh water every two to three days.

Is there a better way of managing your motorhome toilet cassette?

The Dutch company, Thetford, believes there’s a much better way of emptying your tanks, managing your water supplies and staying off grid for longer. 

It’s their new ‘iNDUS smart sanitation system’.

The iNDUS is an integrated sanitation system which uses your water more efficiently than standalone systems. And, it has built-in features to help you use your toilet and grey water chemicals more efficiently. Plus, it makes a cinch to empty it, compared to standard systems.

You’ll start seeing it in new motorhomes soon. Sadly, it’s not available as a retrofit solution.

How does the Thetford iNDUS work? 

The Thetford iNDUS has three tanks in the system, to contain and manage all the water types on board. These are the fresh water tank, the grey water tank (all the waste water from your washing up, or showers), and the black water tank (all your sewage). 

You fill up the fresh water tank, as normal. Every time you wash your hands in your motorhome, or have a shower, for example, the fresh water you used runs off into the grey water tank. And, the water you use in your toilet goes into the black water tank. 

Nothing new here, is there? 

Thetford iNDUS app
The Thetford app

The difference is the tanks work together, controlled by a system which feeds data to an app on your smartphone. More on the app later. 

And, there’s more. The system uses water in your grey water tank to flush the toilet. The grey water isn’t ‘raw’ either. Using Thetford’s Grey Water treatment fluid, the iNDUS system automatically treats the grey water, limiting any smells and keeping the pipes clear.

When your black water is full, the system notifies you through the app. That’s a handy feature to save you from second guessing when it’s time to empty the tank. 

As with the grey water tank, the iNDUS automatically tops up the toilet fluid to keep smell at bay.

There’s also an automatically topped up Thetford flush water additive for your toilet. This will be familiar to anyone with a motorhome.

Thetford fluids, measure for measure


Thetford iNDUS Dosing Module
The Thetford iNDUS Dosing Module

You’ve heard mention of the Thetford fluids above. This is another feature of the new iNDUS sanitisation system. 

Despite our best guesses of how much water we have left in our toilet flush tank. Or, how much water is in either the grey or black water tanks, it’s difficult to judge how much Thetford fluid to add to keep them at the optimal concentrations. 

Thetford realised this was a challenge. They reckon owners top up their fluids every two or three days. And, most of these probably add too much or too little. 

That’s where the Thetford iNDUS steps in. The system takes the guesswork out of adding their fluids to your tanks. It doses them automatically, adding just the right amount to each tank. And, it tells you when the fluid additive containers are low through the app.

Thetford says the fluids will last you about 4 weeks before you need to change them.

Where do you empty a motorhome toilet?

It’s a common question from new and experienced motorhome owners alike. The answer is you empty a motorhome toilet at a campsite or designated spot for motorhomes. 

Thetford app with discharge locations
Thetford app with discharge locations

The Thetford iNDUS app helps with this question too. It helps you locate the nearest place where you can empty your tanks. That’s one less one thing to worry about. 

When you’ve found the nearest place to empty your tanks, dealing with your motorhome black water disposal can be a challenge.

Firstly, with traditional motorhome toilet cassettes, or grey water tanks, you have two problems. You have to either handle the toilet cassette, or park accurately adjacent to where you can drain your grey water tank. It’s a pain. 

Thetford thought of this problem too. It’s ingenious. 

Thetford iNDUS Discharge Module R
The Thetford iNDUS Discharge Module

The iNDUS system has a discharge system which extends from your motorhome to where you drain your black and grey water. The hose is 2 metres long to give you the flexibility of getting your motorhome into position. 

You press a button on the discharge unit on the end of the hose and it empties your tanks. Then, the iNDUS takes some remaining grey water in your tank and flushes the black water tank and the discharge hose. That keeps the system as clean as possible.

The beauty of the discharge unit is it minimises your contact with the black and grey water. It’s more hygienic than traditional black water and grey water systems in motorhomes. 

Is there a Thetford toilet for the iNDUS?

Thetford iNDUS macerator toilet
Thetford iNDUS macerator toilet

Yes, there’s a new Thetford toilet. And, it’s different from normal motorhome flush toilets.

The first you notice is it looks more like a toilet you’d find in your home. It looks modern, has a soft-close seat and lid. And, there’s a new-style bowl design. 

Don’t worry about the weight of it, either. It weighs 7.5 kg, so it’s not going to eat into your payload. 

As mentioned earlier, the toilet uses treated grey water to flush it. Using the grey water means you waste less water, and you use less fresh water. The built-in, two-step macerator pump uses a minimal amount of grey water too. Thetford says the new toilet uses about the same amount of water as their standard cassette toilets.

For a quick flush, the Thetford toilet uses around 200 ml. For a long flush, it’s 500 ml. A home toilet uses between 3 and 10 litres per flush. 

Norbert Van Noesel, Thetford’s head of marketing, stated: 

“By re-using grey water for toilet flushing, people save on average 112 litres of fresh water over four weeks, and, therefore, also the same amount of waste water!”

How will the Thetford iNDUS help you stay off grid?

One of the prime benefits of Thetford’s iNDUS smart sanitisation system is how it makes it easier to stay off grid. 

Thetford believes that, instead of having to call into a campsite or discharge point every two or three days, you can stay off grid for a week.

Stop a moment and think about it. The Thetford iNDUS in your motorhome could be the feature which gives the most freedom. You might have imagined it would be your solar panel and leisure batteries. But, no. It’s your motorhome’s toilet, water and wastewater system.
Find out more about the Thetford iNDUS here:

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